Apparatus for development and completion of wells



United States Patent Uren; Lester C. Petroleum Production Engineering: Oil Field Exploitation. NY, McGraw-l-lill, 3D. Ed., 1953. pp.402- 404. (copy in Group 350) a o n g fo Primary Examiner-Marvin A. Champion Assistant Examiner-Ian A. Calvert Attorney-Wayland D. Keith ABSTRACT: A method of developing and completing wells in a fluid-bearing strata, which strata contains fine micrograin or siltlike sands, clay and mud whereby the strata may be treated with chemicals at various levels, and then the siltlike sand, clay and mud is jetted from the bottom of the well until the fluid is clear and a filter bed of frac sand" is interposed between the strata and the bore of the well, so that the siltlike sand, clay and mud will be prevented from reaching the education tube of the pump. Provision is made for a self-contained filter of frac sand through which the water flows within a jacket which surrounds the casing to additionally filter and cleanse the water of siltlike sand. Further provision is made to agitate the siltlike sand, clay, mud and foreign matter in the well, while a development pump pumps the siltlike sand, clay and mud therefrom. The frac sand is introduced into the top of the well, until the depth of the frac sand is greater than the depth of the fluid-bearing strata, so that the frac sand" will replace the siltlike sand of the fluid bearing strata, as the sand is removed therefrom by jetting and by pumping. Further provision is made to leave a valved air inlet pipe in the well, with the outlet thereof near the bottom of the well, thereby to enable the connection of an air compressor thereto at anytime, to agitate siltlike sand or foreign matter, which may accumulate in the well, to enable the pumping of the sand or the like therefrom.

"PATENIED nan 2 2 I970 SHEET 1 nr 2 FIG. 3

Q 0 o o Ill/l/I/IA- 711 -771 0 on m o m m 1N VENTOR.

[I'll 0 o o a an no HIS AGENT PATENTED m SHEET 2 0F 2 FIG. 4 v5 0 G 0 O O O O o o o 0 0 Q inzladl lnr/ OOOWVo a h m 0 /v ACIE DARREL HARKINS INVENTOR.

/ ms AGENT OOO 0w O O 00 0 0 000 ODOOOD This invention relates to a method of and apparatus for the development and the completion of wells, and to maintaining the wells in satisfactory condition for the production of fluid therefrom, more particularly water wells. In certain areas there is an abundance of fluid, such as water, to be produced from subterranean strata, but due to the type strata from which the water is to be produced, it has not been economically feasible, heretofore, to drill and produce such wells in a formation that contains fine sand which will flow into the well with the water or the like, and which sand could not be restrained from flowing into the well with the water or the like.

Various well completion methods have .been proposed heretofore, such as gravel packs, cementation filters and the like, but these, for the most part, would only temporarily restrain the sand from flowing into the borehole to enable thewater to be pumpedtherefrom, and which filters, or the like, would readilybecome clogged and usually resulted in the untimely abandonment of the well.

The present arrangement for'developing and completing a well and maintaining the well in full production over a long period of time, embodies the steps of lowering a easing into the well, which casing has a perforate annular jacket therearound to receive "frac sand therein to form a filter media, as will be more fully brought out hereinafter. The borehole of the well, exterior of the annular chamber and exterior of the casing, is further filled with frac sand" of specified size to form a filter media to retard the entrance of sand into the borehole of the well. Air and chemicals are introduced into the well under pressure, to cleanse the well of sand, clay and mud that flows thereinto, byjetting the sand, clay and mud therefrom into a disposal pit, until the fluid, such as water, coming from the well, is free of sand, clay and mud, or comparatively so, and is within the usable range of purity for the use to whichsuch water is to be put.

In the development and the completion of wells, such as water wells, and some oil wells, which have fine, siltlike sand therein, great damage is done to pumps, unless this sand, which normally enters the wells, is removed therefrom and entrance of other sand is retarded, so that, after completion of the well, a minimum oflorno sand will flow into the well. Further provision is made for treating the well in event further sand becomes evident in the well to 'such extent that it will cut off the flow of water into the well or will jeopardize the mechanical pumping of the well. I

An object of this invention is to provide an apparatus for the development of and the completion of wells so as to render the wells substantially free of sand flowing into the borehole with the fluid.

Another object of the invention is to provide a system of completion of a well which will enable the fluid being produced to enter the well while substantially all foreign particles are restrained from entering the borehole of the well.

Still another object of the invention is to provide a system of washing a well with chemicals so as to purify the formation and nullify the effect of certain clays andmuds, to enable fluid, such as water, to be produced therefrom without containing mud or other foreign elements.

Yet another object of the invention is to provide for the forcing of chemicals into the fluid-bearing strata so as to dissolve and/or dislocate mud and clay to increase the porosity and production of the strata, particularly water bearing strata.

Still a further object of the invention is to provide a standby cleaning arrangement for the well, to enable any foreign particles coming into the well to be readily agitated with the fluid and removed, without having to rework the well with drilling tools and the like, as has been the practice heretofore.

with these objects in mind and otheis which will become evident as the description proceeds, reference is to be had to the accompanying drawings, in which like reference charac- FIG. 1 is a longitudinal sectional view through a well, showing a casing 2 therein, which casing has a jacket mounted thereon which forms an annular space to receive a filter media therein, with portions being shown in full outline, and with certain portions being shown diagrammatically and other portions being broken away and shortened to bring out the details of construction;

FIG. 2 is a sectional view taken on the line 2-2 of FIG. I, looking in the direction indicated by the arrows;

FIG. 3 is a greatly enlarged, fragmentary sectional elevational view of part of the perforate portion of the wall of the casing, showing the perforations therein and showing an epoxy coating thereon;

FIG. 4 is a view similar to FIG. 1, but taken after initially jetting. sand, clay and mud from the well, and showing a development pump therein, a pipe therein to admit air under pressure to enable agitation of foreign particles which may accumulate in the well, and showing provision for additional filter media, such as frac sand;"

FIG. 5 is a sectional view taken on the line 5-5 of FIG. 4, looking in the direction indicated by the arrows;

FIG. 6 is a sectional view taken on the line 6-6 of FIG. 5, looking in the direction indicated by the arrows;

FIG. 7 is a sectional view taken on the line 7-7 of FIG. 4, looking in the direction indicated by the arrows;

FIG. 8 is an enlarged fragmentary view of the air introduction pipe, as shown in FIG. 4, with portions being broken away and shown in section to bring out the details of construction;

and 1 FIG. 9 is a view similar to FIG. 4 but on a reduced scale, and showing a production pump in the well.

With more detailed reference to the drawing, the numeral l designates generally the borehole of a well, which well has a casing 6 therein, which casing is lowered into the borehole of the well 1, approximately centrally thereof and may either be seated on the bottom 8 of the borehole of the well 1 or it may be suspended from the top of the well 1, as desired. In the present instance, the casing 6 is shown to be seated on the bottom 8 of well 1. The casing 6 has a jacket 10 therearound, which jacket is so arranged, as to be positioned just below the top 12 of the sand formation 14. The jacket 10 has a conical member 16 on the lower end thereof, which member is welded, at 18, to the casing 6 so as to prevent the casing hanging as it is going into the well and to form a closure for the lower end of the jacket. The upper end of the jacket 10 has a conical member 20 thereon-which is welded to the casing 6, as indicated at 21, to form a closure between the jacket 10 and the casing 6.

The size of the casing 6, as well as the size of the jacket, both as to the diameter and as to length,varies in accordance with the particular well conditions, however, as a matter of illustration, a size is given. If the well bore is 20 inches in diameter, and the casing 6 is 12% inches 0.1)., the jacket 10, surrounding the casing 6, could be 16 inches 0.D., which would give approximately 1% inch annular chamber between the outer diameter of the casing 6 and the inner diameter of the jacket 10. With the string of easing 6 having the jacket 10 thereon run into the well, there should be an imperforate portion of the jacket and casing immediately below the top 12 of the water sand 14, which should be from 10 feet to 20 feet in length. The jacket lfthas perforations therein, as shown at 24, for about 72 feet, with 20 gauge to 3/l6-inch perforations. The perforated portion usually extends to a point near where the lower conical member is welded thereto. These perforations 24 are circumferentially spaced so as to permit the free flow of water therethrough into the annular chamber 22 formed between the outer diameter of the casing 6 and the jacket 10. The string of easing has perforations 26 formed therein, which are usually 20 gauge to three-sixteenth inches in diameter and are spaced inward from the perforations 24 in jacket 10.

The length of the jacket, as well as the length of the perters designate like parts in the several views thereof, in which: forated-portion of the jacket and of the casing 6, varies in accordance with the thickness of the fluid-bearing strata 14, such as water, into which the casing is going to be run. The annular chamber 22 may be filled with frac sand" at the time of manufacture of the equipment, and shipped or hauled to the destination to be run into the well, with the frac sand" in place, or the casing 6, having jacket thereon with the conical member 16 welded at the lower end thereof, may be run into the well until the upper end of the jacket 10 is near the top of the well, at which time it may be filled with frac sand" and the member 20 swedged in so as to be conical, which is welded as indicated at 21, then the remaining casing is joined to the upper end thereof for lowering into the well until the casing 6 is to the proper depth or until it seats on the bottom 8 of the borehole of the well 1. The lower end of the casing has a length thereof perforate, by perforations as indicated at 28, usually from 6 to 10 feet, with an imperforate portion of 6 or more feet thereabove which extends to the lower end of the jacket 16.

The portion of the jacket 10 having perforations 24formed therein is coated with epoxy resin 30, as shown in F IG. 3 so none of the metal will be exposed to the abrasive action of the sand passing therethrough.

The casing 6 is likewise coated with an epoxy resin on the portion thereof which is perforated by perforations 26 and 28. A jet pipe 32 is run into casing 6 and is supported by a support member 35 so that the lower end thereof will be a short distance above the bottom 8 of the borehole of the well 1. The jet pipe 32 is provided with a fitting 34 on the upper end thereof, which has a pipe 36 leading therefrom to direct water, sand and the like, dischargedfrom the well, into a pit 38. The fitting 34 has an opening therein, which is closed by a plug 40, which plug maybe removed for the introduction of treatment chemicals and the like and then replaced.

The fitting 34 has a gland body 42 in the top thereof in which a gland 44 is fitted to receive air pipe 46 in sliding relation. An air supply pipe 48 has one end connected to an air pump 49, and the other end is connected to the gland 44 by a union 50, so the air supply pipe 48 may be disconnected for removal of lengths of air pipe 46, which lengths of pipe 46 are joined together as indicated at 52 by flush connections, in a manner well-known in the coupling of pipe. The lengths of pipe are usually 10 to 20 feet long, to permit disconnection thereof to enable removal, as will be more fully brought out hereinafter. The jet pipe 32 may vary in diameter in accordance with the depth of the well and with the amount of air and the pressure of the air used, however, as a matter of illustration, the jet pipe is shown as being 4 inches in diameter, which has been found to be satisfactory in many illustrations. The air pipe 46 is run into the jet pipe 32 and also varies in size in accordance with the amount of air and the pressure of the air to be handled, as well as the depth of the well, however, it has been found that one-half inch to 1% inch diameter pipe makes a suitable air pipe for jetting the sand, clay, mud, contaminated water, and other foreign matter from the well 1. The sizes given are for purposes of illustration only. The lower end of the air pipe 46 is spaced a short distance upward from the lower end of jet pipe 32, so upon introduction of air under pressure into pipe 46, fine sand, clay, mud and foreign matter, which accumulates in the well, will be forced upward in pipe 32 in the annulus between the inner diameter of the jet pipe 32 and the other outer diameter of air pipe 46, which sand, clay, water and air will flow out of the top of jet pipe 32 into fitting 34 into pipe 36 and into pit 38.

With the jet pipe 32 run into the casing 6 in the usual lengths of 20 feet, the lower end of the jet pipe may be raised or lowered as the conditions of the well indicate for proper treatment and completion of the well 1. Likewise, as the lower end of the jet pipe 32 is raised and lowered, the air pipe 46 is raised or lowered accordingly, with the lower end thereof being maintained a spaced distance above the lower end of jet pipe 32. With the jet pipe 32 run to a location near the bottom of the well, a barrel of treating chemical is poured through fitting 34 into the jet pipe 32, and air is introduced into the air line 46. Air pressure, which frequently exceeds 150 pounds, is introduced into air pipe 46 and into the well, then the jet pipe 42 is raised about 20 feet, as well as the air pipe, and an additional barrel of chemical is added into the well through fitting 34 and air pressure is again exerted on the formation, as aforementioned, and this treatment continues through the entire fluid-bearing strata. H

Further steps of treating the well, as well as the chemicals used, will be brought out more fully hereinafter. The support member 35 is provided at the top of the well on which jet pipe 32 and air line 46 are supportedz'The support member 35 further supports a "frac sand" pipe "54, and which has a hopper 56 thereon to enable the introduction of frac,sand" thereinto and therethrough. The frac sand" pipe 54 extends into the well and has the lower end thereof a spaced distance above the static water level 58 in the well 1.

After the well has been initially cleaned offine sand, clay, mud and other foreign material, as briefly brought out above, a development string of pipe 60, having a development pump 62 thereon, is run into the well until a pipe 64, connected to the lower end of the pump 62, extends to or near the bottom 8 of the well 1. The lower portion ,of pipe 64 may be perforated, as indicated at 66, to enable the sand, clay, mud and other foreign material to be withdrawn by the development pump 62, that has not been jetted out of the well by jet pipe 32 under the influence of air from air pipe 46.

An air pipe 68 is run into casing 6 near one side thereof, to a position near the bottom 8 of the well 1, as shown in FIG. 4, which-air pipe 68 has a check valve 70 on the lower end thereof, as shown in FIGS. 4 and 8, which check valve has an upwardly seating valve member 72 therein so that air may be directed downward through pipe 68, at any time, by an air pump or compressor 74. The air compressor 74 has an air supply line 76 leading therefrom, with a separable quickdisconnect coupling 78 therein, so that the air pump or compressor 74 may be disconnected from the air supply line 76 when not in use.

Air may be introduced from air compressor 74 through air line 76 into air pipe 68 and out through check valve 70 to agitate the sand in the lower portion of the well 1, while the development pump 62 is operated. The pump 62 may have a shaft 63 extending upwardly therefrom, if the pump is of the turbine type.

Upon completion of the well with the developmentpump 62, the development pipe 60, and development pump 62 are removed from the borehole of the well 1 and a production pump 80 is run into casing 6, on production pipe 82, so the pump 80 will be submerged below the static fluid level within the well 1. A perforate pipe 84 extends below production pump 80 to enable the pump to withdraw fluid, such as water, from the fluid-bearing strata l4, and to direct the fluid upward through pump 80 and production pipe 82, as will be seen in FIG. 9, to the top of the well. The pump 82 may be driven by a rotating shaft 86, if the pump is of the turbine type, or any other type pump 80. may be used in the production of fluid from the fluid-bearing formation 14. The air pipe 68 is left in the well for use with the production pump 80, to agitate any sand and foreign material to enable the well to be cleaned if needed.

While the completion of the well has been described in some particularity with respect to water-bearing formation, it is to be understood that the present completion method may also be applied to other fluids, such as oil or gas, with the chemicals being varied to suit the conditions of the particular strata being treated. However, frac sand of a size, as will be more fully brought out hereinafter, is used within the perforated jacket 10 and around the jacket 10 and in well casing 6, as will be more fully brought out hereinafter.

I DEVELOPMENT AND COMPLETION OPERATIONOF To develop and complete a fluid producing well in a formation that has micrograin or siltlike'sandther'ein and which sand is usually accompanied with clay and mud, the well is drilled through the fluid-bearing formation and the casing is J then set to the bottom of the well, with the lower 6 feet or so of the casing being perforated to admit micrograin or siltlike sand therethrough. Jet pipe 32- is run into the well until the lower end of the jet pipe is a spaced distance above the bottom 8 of well 1. Lengths of air pipe 46v are run into the jet pipe 32 through stuffing gland 44 until the lower end of the air pipe 46 is a spaced distance upward from the lower end of the jet pipe 32.

With the jet pipe 32 and the air pipe 46 in place, frac sand" 88 is directed through hopper 56 into the annulus formed between the outside diameter ofcasing 6, shell and the wall of the borehole 'of the well 1. The well is filled to within about 50 to 60 feet of the'top, in the manner indicated in FIG. 1, so as to furnish a static head of frac sand" which will move into the voids and replace any sand or other formation, that may be removed from a well by jetting or pumping.

Upon the pipes being locatedin thejrelation as described above, a chemical mixture isprepared comprising, for example, thefollowing proportions: 200 pounds of sodium hexameta phosphate; 2 gallons of sodium xylene sulfonate, and'l gallon of irony! phenyl polyethylene glycol ether containing 9 to 10 moles of ethylene oxide to form a 100 percent nonionic surfactant, to this is added 2 gallons of acetone. These chemicals are admixed with two-thirds of a barrel of water and stirred untildissolved with the resultant mixture being mixed with sufficient water to make 4 barrels of solution. By the ad-' dition of acetone to the heavier chemicals,the specific density of the mixture is adjusted so as to make the density of the mixture the same, or, substantially the same as" the density of water. This allows the mixture to enter the water bearing formation more readily for cleansing of the formation.

The plug 40 is removed from fitting 34 and 1 barrel of the chemical mixture is introduced through jet pipe 32 to a point near the bottom 8 of the well, and then air under pressure of approximately 150 pounds is directed through pipe 46 into the well 1, so as to blow the chemical mixture into the fluid-bearing formation. The pipe'32 is raised approximately feet and another barrel of chemical mixture is introduced into the well and also blown with air to cause the chemical mixture to be dispersed into the formation. Then the pipe 32 is raised another 20 feet and similar treatment given each 20 feet, until the entire fluid-bearing formation has been treated.

Upon the fluid-bearing formation being treated with the chemical mixture in a manner as set out above, the well is allowed to set in' this condition for about 24hours or more, so the chemical will have an opportunity to react with the muds, clays and sands in the formation. After the chemical mixture has been allowedto stay in the formation a sufficient time, usually about 24 hours, to. allow for the proper reaction between the chemical mixture and the muds,'clays and sands,

the jet pipe 32 is lowered to a position near the bottomof thepipe32 and out through'pipe 36 into pit 38. in event the jet pipe 32 cannot be lowered allthe way to the bottom of the well, after treating the well with chemicals, to start the initial jetting, it is lowered to the top ,of the siltlike formation and jetting action is started, and, asthe sand, mud and clay is removed, the pipes are lowered until the lower end of the jet pipe 32 is in closeproximit'y to the bottom 8 of the well 1.

To properly clean the well and remove the siltlike sand, it is usually necessary to perform this operation for several days, and as the micrograin or siltlike sand, mud and clay is removed from the well, the void formed thereby is filled with large grain frac sand, and/or sized aggregate to form a granular material which usually has grains of the size from 4 to 8 mesh size to 10 to 20 mesh size in accordance with the particular well being completed, thereby to properly prevent the greater portion of micrograin sand from flowing into the well, as water is being produced from the formation. 1 With the jetting operation completed, the well having been jetted until the water being produced therefrom is free, or practically free of micrograin sand, clay and mud, the development'pump 62 is run into the casing 6 on development pipe 60. The development pump 62 has a pipe 64 on the lower end thereof with perforations 66 therein. With the development pump 62 seated in the well so that the pipe 64 extends to or near the bottom thereof, the pump is operated to pump water from the well at a high volume towithdraw any contaminated water or chemicals from the fluid-bearing strata l4 and to remove any micrograin sand, mud and clay that might have been produced. into the casing 6.Air may be introduced through pipe 68 and out through check valve 70 to agitate the sand, mud and the like in the bottor'nof the well so that sand, clay, mud and water may be pumped therefrom. The development purnp 62 is usually run continuously for several days until the test of the water shown is free of impurities and chemicals to the desired extent, whereupon, the development,

pump 62, development pipe 60, perforated pipe 64 and shaft 63, are removed from the well and a production pump is run into the well on production pipe 82'with a partially perforated pipe 84 usually extending to thebottom 8 of the well 1.- The lower part of pipe 84 is imperforate for a spaced distance above the bottom of the well to form a mud anchor with the perforations 85 in pipe 84 being immediately below the pump 80, which perforations have sufficient opening area to supply the pump 80 with fluid being pumped without restricting the pump. if the pump 80 is of the turbine-type and is driven by power at the surface of the ground, a drive shaft 86 extends upward from the turbine impellers in pump 80 to the source of power-at the surface of the ground. 7

As the jetting or pumping of the sand, mud and clay from the well is being performed, the frac;sand" 88 moves down the annulus between the well casing 6 and the wall of the well 1 with the frac sand usually reachingthe bottom of the well, as indicated at 88 in FIG. 9.

As the supply of frac sand" 88 lowers in the annulus between the well casing 6 and the wall of the well 1,, additional frac sand" is introduced into hopper 5.6 through pipe 54 into the annulus of the well, so as to maintain a static head of frac sand ready to move into any voids that might be created by the migration of siltlike sand, or clear mud into the borehole of the well. Therefore, as the natural sands from the formation fill the voids between the grains of frac sand," to form a filter for the water which allows the water to flow into the borehole of the well, yet it will be free, or nearly free, of any solids which might impair the purity of the water or injure the pump through abrasive action.

While a specific formula of quantities of chemicals has been set forth, as the best known approximate formula, it is to be pointed out that variation in the amounts of each of these chemicals, with respect to the other ofthe chemicals, may be varied by '50 percent more or 50 percent less and satisfactory results may still be obtained'in certain formations, and in certain formations certain, or all of the chemicals may be dispensed with, and the mechanical completion of the well by jetting, pumping and the use of frac sand" may be practiced with satisfactory results.

I claim:

1. An arrangement for developing and completing a well in a subterraneamporous, fluid-bearing formation of granular 75 material, which arrangement comprises:

a. a well casing, having portions thereof perforated, seated in the borehole of a well to form an annulus between the well casing and the wall of the borehole;

b. granular material, of a size larger than the granular material of the formation, filling the annulus between said well casing and the wall of the borehole;

c. a pipe fitted within said well casing and extending to a position near the lower end thereof;

. pump means within said pipe within said casing intermediate the length thereof to withdraw fluid and loose granular material from the formation into the borehole of the well creating a void in the formation, thereby permitting the granular material within the annulus to move downwardly to fill the void formed in the formation, by the movement of the loose granular material from the formation into the borehole of the well;

e. a portion of said pipe below said pump means being perforate, to withdraw fluids and solids from the lower portion of the well;

. an air'pipe extending downwardly in said casing from the top of the well to a point near the bottom thereof; 1.an air outlet check valve on the lower end of said air pipe; and 2.a source of air connected to said air pipe to agitate fluids and solids in the lower portion of the borehole of the well simultaneously with the operation of the pump means, to enable the development and completion of the well. 2. An arrangement for developing and completing a well in a subterranean, porous, fluid-bearing formation of granular material, which arrangement comprises:

a. a well casing, having portions thereof perforated, seated in the borehole of a well to fonn an annulus between the well casing and the wall of the borehole; b. granular material of a size larger than the granular material of the formation, filling the annulus between the well casing and the wall of the borehole; c. a pipe fitted within the casing and extending to a position near the lower end thereof; I mechanical means associated with said pipe within said casing to withdraw fluidand loose granular material from the formation into the borehole of the well creating a void in the formation, thereby permitting material within the annulus to move downwardly to fill the void formed in the formation, by movement offlthe loose granular material from the formation into the borehole of the well; e. one of said perforated portions of said casing being a spaced distance from the lower end thereof; f. a perforated jacket, of larger diameter than the casing surrounding said last'mentioned perforate portion of said casing to form an annular therebetween; 1.said annulus between said perforate portion of said casing and said jacket being filled with a granular mate rial to form a filter; and H 2.a closure at each end of said jacket to maintain said granular material within said annulus.

3. An arrangement for developing and completing a well, as

defined in claim 2; wherein a. said perforated portions of said casing and said jacket have an epoxy coating thereon and coating the surfaces of said perforate portions. 

